JPS5847902A - Combustor - Google Patents

Abstract

PURPOSE:To obtain stabilized combustion having neither blowing off nor back fire even to a variation of air quantity, by making a space ratio of ventilation of a burner head at the lower stream of a fuel-air mixture flow larger than that at the upper stream of the fuel-air mixture flow. CONSTITUTION:A burner head 13 is constituted with a premeable foaming metal, and density of the foaming metal is varied with the upper stream and the lower stream so that a passing area of a fuel-air mixture inside the burner head 13 at the lower stream is made larger than that at the upper stream. With this, stabilized combustion having neither blowing off nor back fire even to a variation of air quantity is obtained and plane combustion whose variable range is large and radiation is stabilized is carried out.

Description

[Detailed description of the invention]

The present invention relates to a combustion apparatus for burning a mixture of fuel and combustion air, and particularly to an improvement in a combustion apparatus for obtaining radiation by performing combustion on a plane. An example of a conventional combustion device that performs planar combustion is shown in FIG. 1 and will be described. An air supply pipe 4 is opened on one side wall of the vaporization chamber 2 heated by the heater 1 and communicates with the fan 3.

At the same time, the oil supply pipe 6 connected to the oil supply pump 6 is exposed. On the other hand, one end of the air-fuel mixture passage 8 is connected to the opening 7 of the vaporization chamber 2, and a ceramic burner head 10 with a large number of holes 9 is fixed to the other end. An igniter 12 is provided adjacent to the downstream end surface 11 of the head 10. Supplementary note: In the conventional configuration, when the heater 1 is energized to heat the vaporization chamber 2 and reach a predetermined temperature, combustion air is supplied from the fan 3 into the vaporization chamber 2 via the air supply pipe 4, and Liquid fuel is supplied through the fuel supply pipe 6 by a fuel pump. The liquid fuel supplied into the vaporization chamber 2 comes into contact with the heated wall of the vaporization chamber and vaporizes, mixes with combustion air to form an air-fuel mixture, and flows from the L section opening 7 of the vaporization chamber 2 to the air-fuel mixture passage. It flows into 8. The air-fuel mixture that has flowed into the air-fuel mixture passage with a thickness of 1 mm flows out from the numerous holes 9 made in the burner nod 10 while being mixed uniformly, and is ignited by the igniter 12 to perform combustion and burner head 1.0. The downstream end face 11 is heated to remove radiation. However, as shown in Fig. 2-5 in the burner head 10ij in the conventional example, the holes 9 are opened in parallel, which tends to cause thin flame lift and backfire, and the stable combustion area is narrow. It had drawbacks. The reason for this is that in order to heat the downstream end face 11 and obtain radiant metal, it is necessary to form a combustion flame close to the downstream end face 11. Therefore, the flow rate of the air-fuel mixture jetting out from the hole 9 is slow, and it is good in that state. The combustion load, air-fuel ratio, etc. were adjusted to ensure proper combustion. On the other hand, if the combustion air in the mixture increases for some reason, the flow velocity of the mixture ejected from the hole 9 increases, so that the flame surface moves away from the downstream end face 11 until it reaches a position that balances the combustion velocity of the mixture. is formed. Then, the amount of heating of the downstream end surface 11 by the flame decreases, and the temperature of the downstream end surface 11 and the temperature of the mixture ejected from the hole 9 heated thereby decrease. In general, when the temperature of a flammable air-fuel mixture decreases, the combustion rate also decreases, and as a result, the air-fuel mixture ejected from the hole 9 becomes difficult to burn, resulting in blow-off (lift). Conversely, if the amount of air in the air-fuel mixture decreases, the flame front will be formed too close to the downstream end face 11, contrary to the above-mentioned blow-off case, and the downstream end face 11 will be strongly It gets heated and the temperature rises. Therefore, the combustion speed of the air-fuel mixture ejected from the hole 9 increases, and eventually the flame enters the hole 9 from the downstream end face 11, exceeding the ejection speed of the air-fuel mixture ejected from the hole 9. Since the hole 9 has a constant inner diameter, the air-fuel mixture flow rate is constant inside the hole 9, and the combustion speed of the flame once it enters the hole 9 is faster than the air-fuel mixture flow rate inside the hole 9, so the flame moves inside the hole e. proceeds upstream and backfires. Furthermore, when trying to reduce the amount of combustion, it is necessary to reduce the amount of combustion air as well, so as in the case of flashback described above, the flame front approaches the downstream end surface 11. It is easy to cause a backfire. In other words, in the conventional burner head that performs flat combustion, the flame front is formed by touching the metal a certain distance while approaching the downstream end face 11 (combustion surface). They tend to cause lift and backfire, and have a narrow stable combustion range. The present invention addresses the drawbacks of the conventional examples described above, and aims to expand the stable combustion region to perform stable combustion against air amount fluctuations, and to expand the combustion amount variable range.
The above object is achieved by making the flow rate of the air-fuel mixture faster on the upstream side than on the downstream side in the burner head 9 to prevent backfire, and also to form a combustion flame in the burner head e. Next, one embodiment of the present invention is shown in FIG. 3 and will be described. The same numbers in the drawings as in FIG. 1 indicate the same members, and their explanations will be omitted. The burner head 13 is made of breathable foamed metal, and the density (foaming degree) of the foamed metal is adjusted upstream so that the area through which the air-fuel mixture passes through the burner head 13 is small on the upstream side and large on the downstream side. The side and downstream side are different. Therefore,
゛The air-fuel mixture flow speed in the burner head 13 is faster on the upstream side;
The temperature on the downstream side is slower, and stable combustion can be performed in an appropriate part of the burner head even for air-fuel mixtures with different combustion velocities. In the above configuration, the air-fuel mixture supplied from the vaporization chamber 2 is uniformly ejected from the entire surface of the burner head 13 formed of foamed metal, and is ignited by the igniter 12 to perform combustion. The combustion load, air-fuel ratio, etc. are adjusted so that the combustion is carried out at a position where the air-fuel mixture flow rate and combustion speed are balanced. Then, the burner head 13 of the engine 9 is heated by this combustion heat and radiates. At this time, even if the amount of air in the mixture increases for some reason and the flow rate of the mixture increases, the flow rate of the mixture in the burner head 13 is faster on the upstream side and slower on the downstream side, so the amount of air increases. If the air cover increases, the air-fuel mixture flow velocity at the position where combustion was occurring before the combustion will occur at a position downstream of the edge.Then, at that position, the air-fuel mixture flow velocity and combustion speed will balance and combustion will occur. Since the burner head 131 is heated at that part, blow-off (lift) does not occur. Furthermore, since the combustion occurs in a foam, a continuous flame is formed, which prevents local lift, resulting in stable combustion and stable radiation. On the other hand, when the amount of air in the air-fuel mixture decreases, the combustion position moves upstream in the burner head 13, contrary to the above-mentioned case of blow-off (lift), and the air-fuel mixture flow rate increases and the combustion distance increases. The temperatures are balanced, allowing stable combustion without backfire. Also, when reducing the amount of air mixture in order to reduce the amount of combustion, the combustion position in the burner head 13 is on the downstream side, as in the case where the amount of air in the air mixture is reduced as described above. It only moves upstream from the source, and there is no backfire. Moreover, since the combustion device is always located inside the burner head 13, the heating of the burner head 13 is performed stably, and stable radiation can be obtained. In the first embodiment, single foam metal is used for the burner head 13, but foamed ceramic or breathable sintered metal may also be used. Similar effects can be obtained by combining a plurality of different foamed metal plates 14. As is clear from the above explanation, in the present invention, the air-fuel mixture passage area on the upstream side of the air-fuel mixture flow is made smaller in the burner head than on the downstream side so that combustion always takes place within the burner head. As a result, stable combustion without blow-off or flashback can be obtained even when the amount of air fluctuates, and flat combustion with a wide variable range of fuel amount and stable radiation can be achieved by 4'%. A combustion device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a conventional combustion device, FIG. 2 is a sectional view showing a burner head of the conventional combustion device, FIG. 3 is a vertical sectional view of a combustion device in an embodiment of the present invention, and FIG. The figure is a sectional view showing a burner head of another embodiment. 9...Pa/hole, 10...Burner head, 1
1...Downstream end face, 13'...Burner bed. . Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
511 Leg 2 Figure 4

Claims (3)

[Claims] (1) A combustion device in which the space ratio per unit volume of the air-permeable material for burning a mixture of fuel and combustion air is larger on the downstream side of the air mixture flow than on the upstream side. (2) The combustion device according to claim 1, wherein the breathable material is a metal or ceramic formed by foaming or sintering. (3) The combustion device according to claim 1, wherein the burner head is constructed by mounting a plurality of sets of air permeable materials having different space ratios per unit volume.